Heat-dissipating fan

ABSTRACT

A heat-dissipating fan has a housing and an impeller. The housing has a receiving space and one or more guide rings. The receiving space forms an airflow inlet and an airflow outlet. The guide ring is mounted near the airflow outlet and has one or two guide surfaces formed thereon and facing the airflow inlet. The impeller is mounted rotatably in the receiving space and has a hub and multiple blades. Airflow channels formed between adjacent blades each have a cross-section narrowed from a top end of the guide ring to the airflow outlet. Each blade has a receiving notch formed in a bottom edge thereof, corresponding to a cross-section of the guide ring and defines a gap between the blade and the guide ring. Airflow is speeded up in the airflow channels based on Venturi effect, such that a heat-dissipating efficiency of the fan is improved.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heat-dissipating fan, and more particularly to a heat-dissipating fan with an airflow outlet and at least one guide ring mounted at the airflow outlet to increase a speed of exhausting airflow, to raise system impedance and to enhance heat-dissipating efficiency.

2. Description of Related Art

With reference to FIGS. 8 and 9, a conventional heat-dissipating fan (3) in accordance with the prior art has a housing (31), a drive motor and an impeller (32).

The housing (31) has a receiving space (311), a hub bracket (33) and multiple supporting ribs (312). The receiving space (311) is formed in a center of the housing (31) and forms an airflow inlet and an airflow outlet respectively at a top end and a bottom end of the housing (31). The hub bracket (33) is mounted in the receiving space (311). The supporting ribs (312) are formed in the airflow outlet and locate between and connect to the hub bracket (33) and an inner wall of the receiving space (311).

The drive motor has a stator (34) and a rotor. The stator (34) is mounted on the hub bracket (33) and has an axial hole (341) formed in a center thereof.

The impeller (32) has a hub (322), a shaft (321) and multiple blades (323). The hub (322) receives the rotor inside. The shaft (321) is mounted at a center of the hub (322) and is inserted into the axial hole (341). The blades (323) are mounted around an outer wall of the hub (322) and form multiple airflow channels (324) each locating between adjacent blades (323). Therefore, when the impeller (32) rotates, air is sucked from the airflow inlet into the airflow channels (324) and is exhausted from the airflow outlet.

However, the aforementioned heat-dissipating fan does not have enough static pressure, such that the heat-dissipating effect of the conventional fan is inefficient and has a lower system impedance. Currently, electric products have faster and faster processing speed and generate more and more heat, so that how to improve a heat-dissipating efficiency of the heat-dissipating fan is an important subject.

Therefore, the invention provides a heat-dissipating fan to mitigate or obviate the aforementioned problems.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide a heat-dissipating fan which has at least one guide ring to speed up an airflow exhausted from the fan to improve a heat dissipating efficiency.

To achieve the above objective, the heat-dissipating fan has a housing and an impeller. The housing has a receiving space and at least one guide ring. The receiving space is formed in a center of the housing and forms an airflow inlet and an airflow outlet.

The at least one guide ring is mounted near the airflow outlet and each of the at least one guide ring has at least one guide surface formed thereon and facing the airflow inlet.

The impeller is mounted rotatably in the receiving space and has a hub and multiple blades. The blades are mounted around an outer wall of the hub and form multiple airflow channels. Each of the airflow channels locates between adjacent blades and has a cross-section narrowed from at least one top end, respectively, of the at least one guide ring to the airflow outlet. Each of the blades has at least one receiving notch. The at least one receiving notch is formed in a bottom edge of the blade, corresponds to at least one cross-section, respectively, of the least one guide ring and defines at least one gap between the bottom edge of the blade and the at least one guide surface of the at least one guide ring.

Through the aforementioned arrangement, the at least one guide ring is mounted under the blades near the airflow outlet, such that each of the airflow channels formed between adjacent blades is gradually narrowed to speed up the airflow in the airflow channels according to Venturi effect. Additionally, with the guiding effect provided by the at least one guide surface of the at least one guide ring, a period for the blades to accelerate the airflow is prolonged such that the airflow can gain more kinetic energy. Furthermore, the at least one guide ring mounted near the airflow outlet blocks part of the airflow outlet, so that the airflow is prevented from flowing back to the airflow channels when the airflow is reflected by an overheated target device. Additionally, the guide surface can be designed to have different curvatures to concentrate and directly guide the airflow to the target device to achieve an enhanced heat-dissipating efficiency.

Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a first embodiment of a heat-dissipating fan in accordance with the present invention;

FIG. 2 is a side view in partial section of the heat-dissipating fan in FIG. 1;

FIG. 3 is an exploded perspective view of a second embodiment of the heat-dissipating fan in accordance with the present invention;

FIG. 4 is a side view in partial section of the heat-dissipating fan in FIG. 3;

FIG. 5 is a side view in partial section of a third embodiment of the heat-dissipating fan in accordance with the present invention;

FIG. 6 is an exploded perspective view of a forth embodiment of the heat-dissipating fan in accordance with the present invention;

FIG. 7 is a side view in partial section of the heat-dissipating fan in FIG. 6;

FIG. 8 is an exploded perspective view of a conventional heat-dissipating fan in accordance with the prior art; and

FIG. 9 is a side view in partial section of the heat-dissipating fan in FIG. 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIGS. 1 and 2, a first embodiment of a heat-dissipating fan (100) in accordance with the present invention comprises a housing (2), a drive device and an impeller (1).

The housing (2) has a receiving space (21), a hub bracket (23), multiple support ribs (22) and a guide ring (26). The receiving space (21) is formed in a center of the housing (2) and forms an airflow inlet and an airflow outlet. The airflow inlet and the airflow outlet may be formed respectively at a top end and a bottom end of the housing (2). The hub bracket (23) is mounted in the receiving space (21). The support ribs (22) are formed in one of the ends of the receiving space (21) and may be formed in the airflow outlet, as shown in FIG. 1, or in the airflow inlet. The support ribs (22) locate between and connect to the hub bracket (23) and an inner wall of the receiving space (21).

The guide ring (26) is mounted coaxially around an outer wall of the hub bracket (23) near the airflow outlet and has a guide surface (27) formed thereon and facing the airflow inlet. The guide surface (27) may be bevel or streamline and may be formed on an outside of the guide ring (26), wherein the outside is away from the hub bracket (23), as shown in FIG. 2.

The drive device may be a motor and have a stator (24) and a rotor. The stator (24) is mounted on the hub bracket (23) and has an axial hole (25) formed in a center thereof.

The impeller (1) is mounted in the receiving space (21) of the housing (2) and has a hub (11), a shaft (12) and multiple blades (13). The hub (11) receives the rotor inside. The shaft (12) is mounted at a center of the hub (11), protrudes downward and is inserted into to the axial hole (25) in the stator (24) to mount the impeller (1) in the receiving space (21). Accordingly, the rotor in the hub (11) in cooperation with the stator (24) in hub bracket (23) drives the impeller (1) to rotate. The blades (13) are mounted around an outer wall of the hub (11) and form multiple airflow channels (14) each locating between adjacent blades (13) and having a cross-section smoothly narrowing from a top end of the guide ring (26) to the airflow outlet. Each of the blades (13) has a receiving notch (131).

The receiving notch (131) is formed in a bottom edge of the blade (13), corresponds to a cross-section of the guide ring (26) and defines a gap between the bottom edge of the blade (13) and the guide surface (27) of the guide ring (26).

Because the guide ring (26) mounted under the blades (13) near the airflow outlet makes the airflow channels (14) gradually narrowed, when air is sucked from the airflow inlet into the airflow channels (14) by the rotating blades (13) of the impeller (1), airflow is accelerated to pass through the airflow channel (14) according to Venturi effect. Additionally, the guide surface (27) provides a smooth guiding effect to the airflow and prolongs a period for the blades (13) to accelerate the airflow, such that the airflow gains more kinetic energy. Furthermore, a curvature of the guide surface can be designed based on a position on which an overheated target device is mounted, so that the airflow can be effectively guided to the target device to improve an efficiency of heat exchange.

With further reference to FIGS. 3 and 4, in a second embodiment of the heat-dissipating fan (10A), the housing (2A) has a single guide ring (28). The guide ring (28) is mounted on the supporting ribs (22) near the airflow outlet and has two guide surfaces (281) formed thereon and facing the airflow inlet. The guide surfaces (281) may be respectively formed on an outside and an inside of the guide ring (28). The receiving notch (131A) of each blade (13A) of the impeller (1A) corresponds to a cross-section of the guide ring (28) with two guide surfaces (281).

With further reference to FIG. 5, in a third embodiment of the heat-dissipating fan (100B), the housing (2B) has a single guide ring (29). The guide ring (29) is mounted near the airflow outlet and has a guide surface (291) formed thereon and facing the airflow inlet. The guide surface (291) is formed on an inside of the guide ring (29), wherein the inside faces the hub bracket (23). The receiving notches (131B) of the blades (13B) of the impeller (1B) correspond to a cross-section of the guide ring (29).

With further reference to FIGS. 6 and 7, in a forth embodiment of the heat-dissipating fan (100C), the housing (2C) has multiple guide rings (41, 42). The guide rings (41, 42) are mounted on the supporting ribs (22) at intervals near the airflow outlet. As shown in FIG. 6, the housing (2C) has two guide rings (41, 42). Each of the blades (13C) of the impeller (IC) has multiple receiving notches (131C) corresponding to cross-sections, respectively, of the guide rings (29).

Furthermore, the housing (2, 2A, 2B, 2C) may have multiple guide rings (26, 28, 29, 41, 42) including at least one guide ring (26, 29, 41, 42) with a single guide surface (27, 291) and at least one guide ring (28) with two guide surfaces (281) which are arranged at intervals.

With such an arrangement, the heat-dissipating fan can provide advantages as follow:

1. With the arrangement of the guide ring (26, 28, 29, 41, 42), the cross-section of each airflow channels (14) are smoothly narrowed from the top end of the guide ring (26, 28, 29, 41, 42) to the airflow outlet, so that the air is squeezed in the airflow channels (14) to speed up the airflow.

2. With the guiding effect provided by the guide surface (27, 281, 291) of the guide ring (26, 28, 29, 41, 42), the period for the blades (13, 13A, 13B, 13C) to accelerate the airflow is prolonged and the kinetic energy of the airflow is increased.

3. The guide ring (26, 28, 29, 41, 42) is mounted near the airflow outlet to block part of the airflow outlet, so that the air exhausted out of the airflow outlet is prevented from being reflected back to the airflow channels (14) by the target device. Accordingly, air turbulence is avoided and the heat-dissipating efficiency is improved.

4. With proper design of the guide surface (27, 281, 291) of the guide ring (26, 28, 29, 41, 42), the airflow can be concentrated and directly guided to the target device. Additionally, the curvature of the guide ring (26, 28, 29, 41, 42) can be designed based on different target devices to exactly guide the airflow and to enhance the heat-dissipating efficiency.

Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

1. A heat-dissipating fan comprising a housing having a receiving space formed in a center of the housing and forming an airflow inlet and an airflow outlet; and at least one guide ring mounted near the airflow outlet and each one having at least one guide surface formed on the guide ring; and an impeller mounted rotatably in the receiving space and having a hub; and multiple blades mounted around an outer wall of the hub and forming multiple airflow channels, each of the airflow channels locating between adjacent blades and having a cross-section narrowed from at least one top end, respectively, of the at least one guide ring to the airflow outlet, each of the blades having at least one receiving notch formed in a bottom edge of the blade, corresponding to at least one cross-section, respectively, of the at least one guide ring and defining at least one gap between the bottom edge of the blade and the at least one guide surface of the at least one guide ring.
 2. The heat-dissipating fan as claimed in claim 1, wherein the housing further has a hub bracket mounted in the receiving space; and multiple support ribs locating between and connecting to the hub bracket and an inner wall of the receiving space.
 3. The heat-dissipating fan as claimed in claim 2, wherein the at least one guide ring is mounted on the supporting ribs.
 4. The heat-dissipating fan as claimed in claim 1, wherein at least one of the at least one guide ring has a single guide surface.
 5. The heat-dissipating fan as claimed in claim 1, wherein at least one of the at least one guide ring has two guide surfaces.
 6. The heat-dissipating fan as claimed in claim 1, wherein housing has a single guide ring.
 7. The heat-dissipating fan as claimed in claim 1, wherein the housing has multiple guide rings.
 8. The heat-dissipating fan as claimed in claim 7, wherein the guide rings are arranged at intervals and include at least one guide ring with a single guide surface and at least one guide ring with two guide surfaces. 